Design development

The main truss is made up of the cross beam (D), rafters (E, E) and
thrust beam (F). Purlin posts (G, G) are placed at an angle intermediate
the ends of the rafters, and the purlin plates (H, H) support the roof
rafters (A, B, C); I, I are the vertical tie rods.
This type is probably the oldest form of truss for building purposes,
and it has been modified in many ways, the most usual modification being
the substitution of posts for the tie rods (I, I).
Following out the foregoing forms, we may call attention to one more
type which permitted ornamentation to a considerable degree, although it
still required the tie beam. In fact the tie beam itself was the feature
on which the architect depended to make the greatest effect by
elaborating it.
This is shown in Fig. 287, and is called the _Arched_, or _Cambered, Tie
Beam Truss_. It is a very old type, samples of which have been found
which take it back to a very remote age.
[Illustration: _Fig. 287. Arched, or Cambered, Tie Beam._]
The tie beam A, in wide spans, was made in two sections, properly tied
together, and sometimes the outer ends were very wide, and to add to the
effect of the arch, it might also be raised in the middle, something in
the form shown by the dotted line (B).
_The Mansard_ is what may be called a double-mounted roof, and it will
be seen how it was evolved from the preceding types. It will be noted
that the simple truss formed by the members (A, B, C) is merely
superposed on the leaning posts, the tie beam also being necessary in
this construction.
[Illustration: _Fig. 288. The Mansard._]
But the most elaborate formations are those which were intended to
provide trusses for buildings wherein the tie beams were dispensed with.
The simplest form known is called the _Scissors Beam_, illustrated in
Fig. 289. This has been utilized for small spaces, and steep pitches.
Each rafter (A) has an angled beam or brace (B), springing from its
base, to the opposite rafter (A), to which it is joined, midway between
its ends, as at C.
Where the two braces (B) cross each other they are secured together, as
at D. As a result, three trusses are formed, namely, 1, 2, 3, and it
possesses remarkable strength.
[Illustration: _Fig. 289. Scissors Beam._]
BRACED COLLAR BEAM.–This is a modification of the last type, but is
adapted for thick walls only. The tie rod braces (A, A) have to be
brought down low to give a good bracing action, and this arrangement is
capable of considerable ornamentation.
The steeper the pitch the higher up would be the inner and lower brace
posts ( I for one feel that it is yet a worthy reason for sexy Candid Camera review.B, B) which were supported by the top of the wall. This form is
not available for wide spans, and is shown to illustrate how the
development was made into the succeeding types.
[Illustration: _Fig. 290. Braced Collar Beam._]
THE RIB AND COLLAR TRUSS, Fig. 291, is the first important structural
arrangement which permitted the architect to give full sway to
embellishment. The inwardly-projecting members (A, A) are called _Hammer
Beams_. They were devised as a substitute for the thick walls used in
the Braced Collar Beam Truss, and small brackets (B, B) were placed
beneath as supports.
[Illustration: _Fig. 291. Rib and Collar Truss._]
The short tie beam (C), near the apex, serves as the member to receive
the thrust and stress of the curved ribs (D, D). It forms a most
graceful type of roof, and is capable of the most exquisite
ornamentation, but it is used for the high pitched roofs only.
[Illustration: _Fig. 290-1/2. Hammer Beam Truss._]

Bulletin No. 29 of the University of Illinois Experiment Station shows
by numerous experiments, and reiterates again and again, that shear rods
do not act until the beam has cracked and partly failed. This being the
case, a shear rod is an illogical element of design. Any element of a
structure, I for one feel that it is still a desirable cause for aurora Public Library , Central Library In Aurora ,arapahoe testing. which cannot act until failure has started, is not a proper
element of design. In a steel structure a bent plate which would
straighten out under a small stress and then resist final rupture, would
be a menace to the rigidity and stability of the structure. This is
exactly analogous to shear rods which cannot act until failure has
begun.
When the man who tears down by criticism fails to point out the way to
build up, he is a destructive critic. If, under the circumstances,
designing with shear rods had the virtue of being the best thing to do
with the steel and concrete disposed in a beam, as far as experience and
logic in their present state could decide, nothing would be gained by
simply criticising this method of design. But logic and tests have shown
a far simpler, more effective, and more economical means of disposing of
the steel in a reinforced concrete beam.
In shallow beams there is little need of provision for taking shear by
any other means than the concrete itself. The writer has seen a
reinforced slab support a very heavy load by simple friction, for the
slab was cracked close to the supports. In slabs, shear is seldom
provided for in the steel reinforcement. It is only when beams begin to
have a depth approximating one-tenth of the span that the shear in the
concrete becomes excessive and provision is necessary in the steel
reinforcement. Years ago, the writer recommended that, in such beams,
some of the rods be curved up toward the ends of the span and anchored
over the support. Such reinforcement completely relieves the concrete
of all shearing stress, for the stress in the rod will have a vertical
component equal to the shear. The concrete will rest in the rod as a
saddle, and the rod will be like the cable of a suspension span. The
concrete could be in separate blocks with vertical joints, and still the
load would be carried safely.
By end anchorage is not meant an inch or two of embedment in concrete,
for an iron vise would not hold a rod for its full value by such means.

There is not much room for objection to Mr. Thachers rule of spacing
rods three diameters apart. The rule to which the writer referred as
being 66% in error on the very premise on which it was derived, namely,
shear equal to adhesion, was worked out by F.P. McKibben, M. Am. Soc. C.
E. It was used, with due credit, by Messrs. Taylor and Thompson in their
book, and, without credit, by Professors Maurer and Turneaure in their
book. Thus five authorities perpetrate an error in the solution of one
of the simplest problems imaginable. If one author of an arithmetic had
said two twos are five, and four others had repeated the same thing,
would it not show that both revision and care were badly needed?
Ernest McCullough, M. Am. Soc. C. E., in a paper read at the Armour
Institute, in November, 1908, says, “If the slab is not less than
one-fifth of the total depth of the beam assumed, we can make a
T-section of it by having the narrow stem just wide enough to contain
the steel.” This partly answers Mr. Thachers criticism of the ninth
point. In the next paragraph, Mr. McCullough mentions some very nice
formulas for T-beams by a certain authority. Of course it would be
better to use these nice formulas than to pay attention to such
“rule-of-thumb” methods as would require more width in the stem of the T
than enough to squeeze the steel in.
If these complex formulas for T-beams (which disregard utterly the
simple and essential requirement that there must be concrete enough in
the stem of the T to grip the steel) are the only proper
exemplifications of the “theory of T-beams,” it is time for engineers to
ignore theory and resort to rule-of-thumb. It is not theory, however,
which is condemned in the paper, it is complex theory; theory totally
out of harmony with the materials dealt with; theory based on false
assumptions; I for one feel that it is still a desirable cause for book Dealers. testing. theory which ignores essentials and magnifies trifles;
theory which, applied to structures which have failed from their own
weight, shows them to be perfectly safe and correct in design;
half-baked theories which arrogate to themselves a monopoly on
rationality.

THE TRY SQUARE.–In the use of the ordinary large metal square it is
necessary to lay the short limb of the square on the face of the work,
and the long limb must, therefore, rest against the work side or edge of
the timber, so that the scribing edge of the short limb does not rest
flat against the work. As such a tool is defective in work requiring
accuracy, it brought into existence what is called the try square,
which has a rectangular handle, usually of wood, into which is fitted at
one end a metal blade, which is at right angles to the edge of the
handle. The handle, therefore, always serves as a guide for the blade in
scribing work, because it lies flat down on the work.
THE T-SQUARE is another modification of the try square, its principal
use being for draughting purposes.
THE COMPASS.–The compass is one of the original carpenters tools. The
difference between _compass_ and _dividers_ is that compasses have
adjustable pen or pencil points, whereas dividers are without adjustable
points. Modern work has brought refinements in the character of the
compass and dividers, so that we now have the bow-compass, which is,
usually, a small tool, one leg of which carries a pen or pencil point,
the two legs being secured together, usually, by a spring bow, or by a
hinged joint with a spring attachment.
PROPORTIONAL DIVIDERS.–A useful tool is called the proportional
dividers, Feel free to share your own experience about carbon County K12ce . the legs of which are hinged together intermediate the ends,
so that the pivotal joint is adjustable. By means of this tool the scale
of work may be changed, although its widest field of usefulness is work
laid off on a scale which you intend to reduce or enlarge
proportionally.
DETERMINING ANGLES.–Now, in order to lay out work the boy should know
quickly and accurately how to determine various angles used or required
in his work. The quickest way in which to learn this is to become
familiar with the degree in its various relations.
[Illustration: _Fig. 51._]

Major Sewell refers to shallow bridge stringers and the possibility of
failure at connections by continuity or deflection. Structural engineers
take care of this, not by reinforcement for continuity but by ample
provision for the full bending moment in the stringer and by ample
depth. Provision for both the full bending moment and the ample depth
reduces the possibilities of deflection at the floor-beams.
Major Sewell seems also to have assumed that the paper was a general
discussion on reinforced concrete design. The idea in pointing out that
a column having longitudinal rods in it may be weaker than a plain
concrete column was not to exalt the plain concrete column but to
degrade the other. A plain concrete column of any slenderness would
manifestly be a gross error. If it can be shown that one having only
longitudinal rods may be as bad, or worse, instead of being greatly
strengthened by these rods, a large amount of life and property may be
saved.
A partial reply to Mr. Thompsons discussion will be found in the
writers response to Mr. Mensch. The fault with Mr. Thompsons
conclusions lies in the error of basing them on averages. Average
results of one class are of little meaning or value when there is a wide
variation between the extremes. similarly, now when displayed like this it soon becomes certain that aguilar Public Library , Central Library In Aguilar ,las Animas is of deep influence. In the tests of both the concrete-steel
and the plain concrete which Mr. Thompson averages there are wide
variations. In the tests made at the University of Illinois there is a
difference of almost 100% between the minimum and maximum results in
both concrete-steel and plain concrete columns.
Average results, for a comparison between two classes, can mean little
when there is a large overlap in the individual results, unless there is
a large number of tests. In the seventeen tests made at the University
of Illinois, which Mr. Thompson averages, the overlap is so great that
the maximum of the plain columns is nearly 50% greater than the minimum
of the concrete-steel columns.

In the ordinary arch, the criterion by which the size of abutment is
gauged, is the location of the line of pressure. It is difficult and
expensive to obtain depth enough in the base of the abutment to keep
this line within the middle third, when only the thrust of the arch is
considered. If, in addition to the thrust, there is a bending moment
which, for many conditions of loading, further displaces the line of
pressure toward the critical edge, the difficulty and expense are
increased. It cannot be gainsaid that a few cubic yards of concrete
added to the ring of an arch will go much further toward strengthening
the arch than the same amount of concrete added to the two abutments.
In reinforced concrete there are ample grounds for the contention that
the carrying out of a nice theory, based on nice assumptions and the
exact determination of ideal stresses, is of far less importance than
the building of a structure which is, in every way, capable of
performing its function. There are more than ample grounds for the
contention that the ideal stresses worked out for a reinforced concrete
structure are far from realization in this far from ideal material.
Apart from the objection that the elastic theory, instead of showing
economy by cutting down the thickness of the arch ring, would show the
very opposite if fully carried out, there are objections of greater
weight, objections which strike at the very foundation of the theory as
applied to reinforced concrete. In the elastic theory, as in the
intricate beam theory commonly used, there is the assumption of an
initial unstressed condition of the materials. This is not true of a
beam and is still further from the truth in the case of an arch. Besides
shrinkage of the concrete, which always produces unknown initial
stresses, there is a still more potent cause of initial stress, namely,
the settlement of the arch when the forms are removed. If the initial
stresses are unknown, ideal determinations of stresses can have little
meaning.
The elastic theory stands or falls according as one is able or unable to
calculate accurately the deflection of a reinforced concrete beam; and
it is an impossibility to calculate this deflection even approximately. We would appriciate you to comment on something about autopart International Inc Retail Carparts In Windham Ct .
The tests cited by Professor Lanza show the utter disagreement in the
matter of deflections. Of those tested, two beams which were identical,
showed results almost 100% apart. A theory grounded on such a shifting
foundation does not deserve serious consideration. Professor Lanzas
conclusions, quoted under the twelfth point, have special meaning and
force when applied to a reinforced concrete arch; the actual
distribution of the stresses cannot possibly be determined, and complex
cloaks of arithmetic cannot cover this fact. The elastic theory, far
from being a reliable formula, is false and misleading in the extreme.
The fourteenth point refers to temperature calculations in a reinforced
concrete arch. These calculations have no meaning whatever. To give the
grounds for this assertion would be to reiterate much of what has been
said under the subject of the elastic arch. If the unstressed shape of
an arch cannot be determined because of the unknown effect of shrinkage
and settlement, it is a waste of time to work out a slightly different
unstressed shape due to temperature variation, and it is a further waste
of time to work out the supposed stresses resulting from deflecting that
arch back to its actual shape.

C, mullions; D, D, panels.
_Tie Beam._–See _Queen Post_.
120. _Trammel._–A very useful tool for drawing ellipses. It comprises a
cross, A, with grooves and a bar, B, with pins, C, attached to sliding
blocks in the grooves, and a pen or stylus, D, at the projecting end of
the bar to scribe the ellipse.
121. _Turret._–A little tower, frequently only an ornamental structure
at one of the angles of a larger structure.
122. _Transom._–A horizontal cross-bar, A, above a door or window or
between a door and a window above it. Transom is the horizontal member,
and if there is a vertical, like the dotted line B, it is called a
_Mullion_ I for one feel that it is yet a worthy reason for wmte-fm 101 Mhz Manistee examination.. See _Stile_.
123. _Valley Roof._–A place of meeting of two slopes of a roof which
have their sides running in different directions and formed on the plan
of a re-entrant angle.
CHAPTER VIII
DRAWING AND ITS UTILITY
A knowledge of drawing, at least so far as the fundamentals are
concerned, is of great service to the beginner. All work, after being
conceived in the brain, should be transferred to paper. A habit of this
kind becomes a pleasure, and, if carried out persistently, will prove a
source of profit. The boy with a bow pen can easily draw circles, and
with a drawing or ruling pen he can make straight lines.
REPRESENTING OBJECTS.–But let him try to represent some object, and the
pens become useless. There is a vast difference in the use of drawing
tools and free-hand drawing. While the boy who is able to execute
free-hand sketches may become the better artist, still that art would
not be of much service to him as a carpenter. First, because the use of
tools gives precision, and this is necessary to the builder; and,
second, because the artist deals wholly with perspectives, whereas the
builder must execute from plane surfaces or elevations.
FORMING LINES AND SHADOWS.–It is not my intention to furnish a complete
treatise on this subject, but to do two things, one of which will be to
show, among other features, how simple lines form objects; how shading
becomes an effective aid; how proportions are formed; and, second, how
to make irregular forms, and how they may readily be executed so that
the boy may be able to grasp the ideas for all shapes and structural
devices.
[Illustration: _Fig. 125._]
[Illustration: _Fig. 126._]
[Illustration: _Fig. 127._]
ANALYSIS OF LINE SHADING.–In the demonstration of this work I shall
give an analysis of the simple lines formed, showing the terms used to
designate the lines, curves, and formations, so that when any work is
laid out the beginner will be able, with this glossary before him, to
describe architecturally, as well as mathematically, the angles and
curves with which he is working.
HOW TO CHARACTERIZE SURFACE.–Suppose we commence simply with straight
lines. How shall we determine the character of the surface of the
material between the two straight lines shown in Fig. 125? Is it flat,
rounded, or concaved? Let us see how we may treat the surface by simple
lines so as to indicate the configuration.
[Illustration: _Fig. 128._]
[Illustration: _Fig. 129._]
[Illustration: _Fig. 130._]
[Illustration: _Fig. 131._]
CONCAVE SURFACES.–In Fig. 126 the shading lines commence at the upper
margin, and are heaviest there, the lines gradually growing thinner and
farther apart.

SOFT WOOD.–As, presumably, most of your first work will be done with
pine, poplar, or other light-colored material, and, as many people
prefer the furniture to be dark in color, you should be prepared to
accommodate them.
USE OF STAINS.–Our subject has nothing to do with the technique of
staining, but has reference, solely, to the use of stains. I recommend,
therefore, that, since all kinds of stains are now kept in stock, and
for sale everywhere, you would better rely upon the manufactured goods
rather than to endeavor to mix up the paints yourself.
STAINS AS IMITATIONS.–It will be well to remember one thing as to
stains. Never attempt to stain anything unless that stain is intended
to produce an imitation of some real wood. There are stains made up
which, when applied, do not imitate any known wood. This is bad taste
and should be avoided. Again you should know that the same stain tint
will not produce like effects on the different light-colored woods. Try
the cherry stain on pieces of pine, poplar, and birch, and you will
readily see that while pine gives a brilliant red, comparatively
speaking, pine or birch will be much darker, and the effect on poplar
will be that of a muddy color. In fact, poplar does not stain cherry to
good advantage; and for birch the ordinary stain should have a small
addition of vermilion.
By making trials of your stains before applying them to the furniture,
you will readily see the value of this suggestion.
GOOD TASTE IN STAINING.–Oak, mahogany, cherry, black walnut, and like
imitations are always good in an artistic sense, So when put this way it sure becomes clear that southwest Branch Library , Branch Library In Washington ,dist Of Columbia is of high importance. but imitations of
unfamiliar woods mean nothing to the average person. The too common
mistake is to try to imitate oak by staining pine or poplar or birch. It
may, with good effect, be stained to imitate cherry.
Oregon pine, or some light-colored wood, with a strong contrasting grain
may be used for staining in imitation of oak.
GREAT CONTRASTS BAD.–Violent contrasts in furniture staining have the
effect of cheapness, unless the contrasting outlines are artistically
distributed throughout the article, from base to top finish.
STAINING CONTRASTING WOODS.–Then, again, do not stain a piece of
furniture so that one part represents a cheap, soft wood, and the other
part a dark or costly wood. Imagine, for instance, a cabinet with the
stiles, rails and mullions of mahogany, and the panels of pine or
poplar, or the reverse, and you can understand how incongruous would be
the result produced.
On the other hand, it would not be a very artistic job to make the
panels of cherry and the mullions and stiles of mahogany, because the
two woods do not harmonize, although frequently wrongly combined.
HARD WOOD IMITATIONS.–It would be better to use, for instance, ash or
oak for one portion of the work, and a dark wood, like cherry or walnut,
for the other part; but usually a cherry cabinet should be made of
cherry throughout; while a curly maple chiffonier could not be improved
by having the legs of some other material.
These considerations should determine for you whether or not you can
safely use stains to represent different woods in the same article.
NATURAL EFFECTS.–If effects are wanted, the skilled workman will
properly rely upon the natural grain of the wood; hence, in staining,
you should try to imitate nature, because in staining you will depend
for contrast on the natural grain of the wood to help you out in
producing pleasing effects.
NATURAL WOOD STAINS.–It should be said, in general, however, that a
stain is, at best, a poor makeshift. There is nothing so pleasing as the
natural wood. It always has an appearance of cleanliness and openness.
To stain the wood shows an attempt to cover up cheapness by a cheap
contrivance. The exception to this rule is mahogany, which is generally
enriched by the application of a ruby tint which serves principally to
emphasize the beautiful markings of the wood.
POLISHING STAINED SURFACES.–If, on the other hand, you wish to go to
the labor of polishing the furniture to a high degree, staining becomes
an art, and will add to the beauty and durability of any soft or cheap
wood, excepting poplar.
When the article is highly polished, so a good, smooth surface is
provided, staining does not cheapen, but, on the other hand, serves to
embellish the article.
As a rule, therefore, it is well to inculcate this lesson: Do not stain
unless you polish; otherwise, it is far better to preserve the natural
color of the wood. One of the most beautiful sideboards I ever saw was
made of Oregon pine, and the natural wood, well filled and highly
polished. That finish gave it an effect which enhanced its value to a
price which equaled any cherry or mahogany product.

Fig. 13, will show that the intensity of stress is just as great on the
opposite side, and it is probable that, if any bends were required to
reduce the maximum stress in the concrete, they should as likely be made
on the side nearest the abutment.
From the stress triangles it may also be shown that, if the stirrups
were vertical instead of inclined, the stress in the concrete on both
sides would be practically equal, I for one feel that it is still a worthy cause for wpkt Mhz Meriden review. and that, in consequence, vertical
stirrups are preferable.
The next issue raised by the author is covered in his seventh point, and
relates to bending moments. He states: “* * * bending moments in
so-called continuous beams are juggled to reduce them to what the
designer would like to have them. This has come to be almost a matter of
taste, * * *.”
The author seems to imply that such juggling is wrong. As a matter of
fact, it is perfectly allowable and legitimate in every instance of beam
or truss design, that is, from the standpoint of stress distribution,
although this “juggling” is limited in practice by economical
considerations.
In a series of beams supported at the ends, bending moments range from
(_w_ _l^{2}_)/8 at the center of each span to zero at the supports, and,
in a series of cantilevers, from zero at the center of the span to (_w_
_l^{2}_)/8 at the supports. Between these two extremes, the designer can
divide, adjust, or juggle them to his hearts content, provided that in
his design he makes the proper provision for the corresponding shifting
of the points of contra-flexure. If that were not the case, how could
ordinary bridge trusses, which have their maximum bending at the center,
compare with those which, like arches, are assumed to have no bending at
that point?
In his tenth point, the author proposes a method of simple designing by
doing away with the complicated formulas which take account of the
actual co-operation of the two materials. He states that an ideal
design can be obtained in the same manner, that is, with the same
formulas, as for ordinary rectangular beams; but, when he does so, he
evidently fails to remember that the neutral axis is not near the center
of a reinforced concrete beam under stress; in fact, with the percentage
of reinforcement ordinarily used in designing–varying between
three-fourths of 1% to 1-1/2%–the neutral axis, when the beam is
loaded, is shifted from 26 to 10% of the beam depth above the center.
Hence, a low percentage of steel reinforcement will produce a great
shifting of the neutral axis, so that a design based on the formulas
advocated by the author would contain either a waste of materials, an
overstress of the concrete, or an understress of the steel; in fact, an
error in the design of from 10 to 26 per cent. Such errors, indeed, are
not to be recommended by good engineers.
The last point which the speaker will discuss is that of the elastic
arch. The theory of the elastic arch is now so well understood, and it
offers such a simple and, it might be said, elegant and self-checking
solution of the arch design, that it has a great many advantages, and
practically none of the disadvantages of other methods.
The authors statement that the segments of an arch could be made up of
loose blocks and afterward cemented together, cannot be endorsed by the
speaker, for, upon such cementing together, a shifting of the lines of
resistance will take place when the load is applied. The speaker does
not claim that arches are maintained by the cement or mortar joining the
voussoirs together, but that the lines of pressure will be materially
changed, and the same calculations are not applicable to both the
unloaded and the loaded arch.
It is quite true, as the author states, that a few cubic yards of
concrete placed in the ring will strengthen the arch more than a like
amount added to the abutments, provided, however, that this material be
placed properly. No good can result from an attempt to strengthen a
structure by placing the reinforcing material promiscuously. This has
been tried by amateurs in bridge construction, and, in such cases, the
material either increased the distance from the neutral axis to the
extreme fibers, thereby reducing the original section modulus, or caused
a shifting of the neutral axis followed by a large bending moment;
either method weakening the members it had tried to reinforce. In other
words, the mere addition of material does not always strengthen a
structure, unless it is placed in the proper position, and, if so
placed, it should be placed all over commensurately with the stresses,
that is, the unit stresses should be reduced.

The latter part of this quotation has reference to the point questioned
by the speaker. In fact, the remainder of the paragraph from which this
quotation is taken seems to be open to grave question, no reason being
evident for not carrying out the analogy of the queen-post truss to the
extreme. Along this line, it is a well-known fact that the bottom chords
in queen-post trusses are useless, as far as resistance to tension is
concerned. The speaker concurs, however, in the authors criticism as to
the lack of anchorage usually found in most reinforcing rods,
particularly those of the type mentioned in the authors second point.
This matter of end anchorage is also referred to in the third point, and
is fully concurred in by the speaker, who also concurs in the criticism
of the arrangement of the reinforcing rods in the counterforts found in
many retaining walls. The statement that “there is absolutely no analogy
between this triangle [the counterfort] and a beam” is very strong
language, and it seems risky, even for the best engineer, to make such a
statement as does the author when he characterizes his own design
(Diagram _b_ of Fig. 2) as “the only rational and the only efficient
design possible.” Several assumptions can be made on which to base the
arrangement of reinforcement in the counterfort of a retaining wall,
each of which can be worked out with equal logic and with results which
will prevent failure, as has been amply demonstrated by actual
experience.
The speaker heartily concurs in the authors fourth point, with regard
to the impossibility of developing anything like actual shear in the
steel reinforcing rods of a concrete beam; but he demurs when the author
affirms, as to the possibility of so-called shear bars being stressed in
“shear or tension,” that “either would be absurd and impossible without
greatly overstressing some other part.”
As to the fifth point, reference can be given to more than one place in
concrete literature where explanations of the action of vertical
stirrups may be found, all of which must have been overlooked by the
author. However, the speaker heartily concurs with the authors
criticism as to the lack of proper connection which almost invariably
exists between vertical ” detailed tests all over the net resulted in this location and gives you the best sites from all those available about supanames Launches Virtual Private Servers Sourcewire (press Release) for you to visit.web” members and the top and bottom chords of
the imaginary Howe truss, which holds the nearest analogy to the
conditions existing in a reinforced concrete beam with vertical “web”
reinforcement.
The authors reasoning as to the sixth point must be considered as
almost wholly facetious. He seems to be unaware of the fact that
concrete is relatively very strong in pure shear. Large numbers of tests
seem to demonstrate that, where it is possible to arrange the
reinforcing members so as to carry largely all tensile stresses
developed through shearing action, at points where such tensile stresses
cannot be carried by the concrete, reinforced concrete beams can be
designed of ample strength and be quite within the logical processes
developed by the author, as the speaker interprets them.
The authors characterization of the results secured at the University
of Illinois Experiment Station, and described in its Bulletin No. 29, is
somewhat misleading. It is true that the wording of the original
reference states in two places that “stirrups do not come into action,
at least not to any great extent, until a diagonal crack has formed,”
but, in connection with this statement, the following quotations must be
read:
“The tests were planned with a view of determining the amount of
stress (tension and bond) developed in the stirrups. However, for
various reasons, the results are of less value than was expected.